But arguably the best representation of Cortana's potential dates back to 2011, well before the current crop of rumors had begun to sprout. Microsoft produced a video to demonstrate how TellMe, the speech-recognition technology it acquired in 2007, might evolve. The video focuses on a smartphone interface that superficially resembles the iPhone's Siri, but that is substantially more responsive to conversational language. The Microsoft virtual assistant is shown handling complex requests with ease; rather than simply aggregating Web returns, for example, it makes complex recommendations that involve the user's location, friends' recommendations, and even criteria such as whether a venue has open-air space. The video shows the virtual assistant's content being easily transferred to a TV, where users use a gesture-based interface to engage content. It also shows the content on a tablet with a vaguely tile-based UI.

The video, in other words, depicts a blueprint in which personalized information is automatically shared between Windows Phone 8 handsets, Windows 8 tablets and TVs connected to the Xbox One. It's the "one Microsoft" ideal in the flesh: Many products combined into a single, cohesive and unique user experience.

If Microsoft releases a digital assistant that actually leapfrogs competitors, it could bolster many of the "one Microsoft" strategies of which investors are most suspicious. Even if the technology is only available on smartphones when it launches, it would bolster Windows Phone 8, which has solidified itself as the third major handset platform, behind Android and iOS, and which is making impressive gains in emerging markets. Apple's failure to meaningfully improve Siri has been one of iOS's ongoing letdowns, and Microsoft could send a powerful message if it reaches the next stage ahead of its rivals.

Indeed, if Microsoft expands Cortana into a larger, ecosystem-wide service, the impact could be immense. Microsoft has tried so far to sell Windows 8 on the strength of laptop-tablet convergence, and on mobile access to Microsoft Office. Neither tactic has worked, and many have criticized Microsoft's insistence on pursuing consumers. If Cortana delivers a unified experience that lives up to Weitz's grandstanding, Microsoft could have the killer consumer app that it needs, one that not only sells individual products but also incentivizes users to adopt other products within the Windows ecosystem.

Cortana would also demonstrate why Microsoft has resisted investor pressure to abandon Bing. The search engine has lost billions of dollars, and even its defenders credit it mostly for blocking Google's would-be monopoly. But if Bing becomes the lifeblood of other product lines and revenue streams, Microsoft's persistence could prove wise in the long run. It would blend the Windows RT kernel, Bing, Azure and a number of other disparate technologies under a single user experience, achieving the kind of product cohesion that Ballmer's critics say the company has lacked under his leadership.

It's not clear how quickly Microsoft will debut Cortana, nor how much functionality the assistant will have if it debuts with Windows Phone 8.1. There is also no known timeline for Cortana's expansion to other elements of the Windows ecosystem. But Microsoft demonstrated with its Nokia acquisition that it is serious about catching up in the mobile arena. A truly cutting-edge digital assistant could be just the weapon it needs to lead the charge.

Michael, Do you see Cortana being able to bridge someone's personal and work content? For example, if I had a Win8 device, could I ask questions based on my corporate Outlook account or even the Word Docs on my PC?

That's a great question, Lorna. To some extent, I think so, but it will probably get tricky. It's one thing for Cortana to scan my personal email; it's my email, after all. But if it's a corporate account, I, as the user, wouldn't have the authority to authorize that kind of scan-- at least not without oversight of some kind. How granularly could Microsoft allow IT to restrict content without detracting from Cortana's strengths? If there's a work-personal separation, is it elegant and simple, or is it as clunky and annoying to the end user? Microsoft has all the money and security expertise in the world to throw at this problem. But this is a different sort of puzzle, I think.

Good point. But Microsoft had several years to learn from iOS and Android before it finally launched Windows 8 and Windows RT, and the extra time didn't exactly help. We know Microsoft's been watching and taking notes-- but will it come to the right conclusions? Its potential sounds tantalizing, but the tech industry is littered with the dead carcasses of failed "game changers."

Your question, Lorna, is exactly why Google Now is of so little interest to me: unless I'm missing something, it only does searches. Sure, it may do a better job of presenting the results than Siri, but it's a one-trick pony. If what you want isn't a search, it isn't going to help you.

Siri, on the other hand, can schedule appointments, initiate calls, initiate texts, initiate emails, take dictation, adjust system settings, tell me the weather, get me directions, play my music, set alarms, lookup addresses, and a ton more ... including searching the web for info. Siri is invaluable to me, especially when I'm in the car and can't type or shouldn't be looking at my phone.

For Cortana to improve upon Siri or Now, MS can't just rely upon Bing, it needs to out-Siri Apple with all the local stuff that you're asking about AND out-Now Google's search results. And, if history has shown us anything, it's that MS is a better follower than leader when it comes to such endeavours. MS has an unbeatable ability to make "good enough" copies of others' (often Apple's ... or Google's ... or Netscape's ... or Novell's ... or whomever's) solutions that most folks will be willing to settle for if they can't use the Real McCoy solution for whatever reason.

The natural language translation in MS' TellMe demo video was impressive, but it was just a demo. Apple had a similar one way back in 1987 (the Knowledge Navigator: http://www.youtube.com/watch?v.... The real proof is in the pudding, and I suspect Cortana will be a few ingredients short. Then again, it might just be good enough for the masses.

Lots of good points. Microsoft is talking a good game in the abstract-- but it's all vaporware at this point. Still, if the technology is really supposed to anchor a major part of the "one Microsoft" vision, Microsoft has to believe it has something special, right?

It's going to take a long time before people are really comfortable talking to virtual assistants. You can experiment with the Web and figure out how things work but I've yet to see anyone do the same kind of experimentation out load with voice recognition software, perhaps because it's frustrating to speak and not be understood.

That's a great point. A speech-based virtual assistant takes more of an investment from the user. The payoff has to be obvious and appealing, and the learning curve can't rely too heavily on awkward commands. There's a lot of complexity in developing for this sort of interaction model that's just not present in other models.